houston



B. THOMSON & E. J. HOUSTON.

Automatic Adjuster for Oomrn-utator-Brushes on Magneto-ElectricMachines.

No. 223,659. Patented Jan. 20, I880.

INVENTORS. .x Q1,

I'LPETERS, PHOTO-LITHOGRAPHER. WASHINUTON, D C.

UNITED STATES PATENT OFFICE.

ELIHU THOMSON AND EDTVIN J. HOUSTON, OF PHILADELPHIA, PA.

AUTOMATIC ADJUSTER FOR COMMUTATOR-BRUSHES N MAGNETO-ELECTRIC MACHINES.-

SPECIFICATION forming part of Letters Patent No. 223,659, dated January20, 1880.

I Application filed November 3, 1879.

To all whom it may concern Be it known that we, ELIHU THOMSON and EDWINJ. HOUSTON, both of the city and county of Philadelphia, Pennsylvania,have invented a novel method and device for the antomatic adjusting ofthe collectors or brushes applied to the commutators of dynamo-electricmachines, whereby an automatic adaptation to variations ofcircuit-resistancesis secured, and the burning and destructive effectsof false adjustments obviated.

It is a fact well known in the art that the greatest freedom fromburning and irregular action is secured when the collecting-brushesoccupy a certain position, dependent in any given case on the speed ofmotion and resistance interposed in the outside circuit. A variation ofeither the speed or the resistance occasions a necessity forreadjustment of the commutator collecting-strips. After an adjustmenthas once been made no readjustment would be required were itpracticableto maintain a uniform speed of rotation of the armature and a constantresistance of the circuit.

Attempts have hitherto been made to adjust the commutator-collectors bycausing a centrifugal device to move forward said collecting-brushes onan increase in the speed of rotation of the armature, and to retract orreverse said motion on a decrease in the speed of running. Such anarrangement fails in its purpose when variations in thecircuit-resistance are occurring at the same time.

By combiningthe force of centrifugal action, dependent 011 speed, withmagnetic force, dependenton current variation, at moreperfectlyoperating device is secured.

Figurel shows one of the ways in which said actions may be combined forsecuring the automatic adjustment of the commutator collecting-brushes.

The commutator K is mounted on a rotating shaft. 0 O are thecollecting-brushes applied to said commutator. A spring, S, tends tomove the collectors O O in the opposite direction to that of revolutionof the commutator K, as shown by the arrow. A flexible cord, t, attachedto the supports of the collecting-brushes O 0, passes around a pulley,1?, supported by the lever L. The supports of the collectors U G arefree to move around the commutator-axis. The lever L and pulley P aremoved by an electromagnet, M, whose coils are traversed by the currentof the machine, ora shunted portion thereof, attracting its armature N,as shown. The other end of the cord t is attached to a lever, L, theposition of which is regulated by the centrifugal action of the governorG in a well-known manner. The adjustments are such that an increase inthe current strength, or an increase in the speed of rotation, or bothtogether, act to cause the collectors O O to move forward in thedirection of rotation, as shown by the arrow, and against the tension ofthe spring S, which spring serves to cause an opposite motion of thecollectors 01.1 a decrease in the current, or a decrease in the speed,or both; but the proper adjustment of the range of motion to be impartedin each case is an operation requiring great nioety, to obviate which wehave devised a method of operating by which the amount of motion to beimparted to the collectors is directly dependent upon the action of thecollectors themselves in receiving current from the commutator. We arethus enabled to dispense with the centrifugal regulation.

The principle of our present invention may be briefly stated: WVeprovide, in addition to the ordinary collecting-brushes, small accessorybrushes, (one or more,) which serve to re ceive current from thecommutator segments after they have passed out of contact with the maincollectin g-brushes. The current received by the accessory collectorspassed through the coils of an electro-magnet serves to throw in or outof action any suitable motor device attached to the colleetingbrushesfor their adjustment. After passing through said electro-magnet, thecurrent from the accessory collector joins that from the main collector.The device for moving the commutator may be adapted to move by thecurrent, or by the motive power, or by suitable clock-work or othermechanism adapted to be thrown in or out of action by an electro-magnet,and constitutes, therefore, an unessential feature of the invention.

In the description which follows we have assumed that the motor deviceselected is to be operated by a shunted portion of the current developedby the machine, and this we find in practice to be a most convenientdisposition for the purpose.

In Fig. 2, K K K represent the segments of a commutator arranged in asuitable manner, and of which any number may be employed.

O b are the main collectors, as ordinarily used. in addition to these,we apply accessory collectors C (one or more,) which may be of muchsmaller width than the main collectors O O, and which rest upon thesegments K K K somewhat in advance of the main collectors O O, as shown.The accessory collector G which in the figure serves to operate theadjusting device, is electrically connected to the main collectorcorresponding thereto through the coils of an electro-magnet, A, which,attracting its armature B, can establish electrical contact between thecontactpicces p q, as shown.

A regulable spring, S, holds the armature B away from the magnet A whenno current is passing. The collectors O O are mounted upon a swingingbar, B, so as to rock concentrically with the shaft bearing thecommutator K K K.

A connecting-rod, l, joins the rocking supports 1t 1% of the collectors,and the lever L is moved by the attraction of the electro-magnet M uponits armature N against the regulable tension of the spring S. Adash-pot, D, serves to prevent too sudden and violent change of positionof the lever L.

The coils of the electro-magnet M are placed in a shunt-circuit throughthe contact-points p 1 around a part of the comLlu'cting-wire of themachine as, for example, the field-magnet coilsthe object being simplyby the contact of the points 1) and q to divert a suliicient portion ofthe current through the electromagnct M for the movement of thecollectingbrushes (1 (J, as determined by said contacts.

As we have before stated, any motor device operated by the magnet A orits armature B, and serving to fulfill the purpose of the mag net M andlever L, may be used, as convenience determines.

Our invention may be applied to any commutator composed of segments orconducting strips arranged around an axis, the principle of operationremaining the same. When applied to thePaccinotti commutator in itsvarious forms, we prefer to polarize the armature B, or theelectro-magnet A, or both, so that on the passage of a current throughthe magnet A in one direction it shall attract its armature B, but whenthe current is in the other direction said armature shall be released orrepelled.

The method of operation is as follows, viz: Assuming the segments K andK to be in contact at a certain part of the revolution with the brushesC and C, respectively, and thatsaid segments are of unequal electricalpotential, and in consequence the brushes 0 and C, respectively incontact therewith, are also of unequal electrical potential, a currentwill flow during said di Herence of potential through the electro-magnetcoils A, tending to equalize the potentials of G and G. The armature Bis therefore attracted and the electrical contact made at p q, thuscausing current to circulate through the coils of the electro-magnet M,which, in turn, attracts its armature N, the lever L being moved therebyand its -motion transmitted to the commutator-collectors C O C 0 throughthe connecting-rod Z and the rocking supports R 1, thus effecting suchan adjustment of said collectors as will equalize their potentials, atwhich moment the current through the electro-magnet A ceases, the springS breaks the contact at 12 q, and the armature N, in consequence, beingreleased, motion in the opposite direction is be gun, to be immediatelychecked or resumed in the former direction when a difference ofpotential of the brushes (J and 0 again manifests itself. The accessorycollector C may be used, if desired, to assist C or it may be directlyconnected to the main collector U, or in certain cases completelydispensed with, as with a proper adjustment effected on one side of theaxis the opposite collector may be set in a position correspondingthereto. \Vhen the brushes and O are thus secured of an equal potentialthe operation of the commutator is characterized by the absence ofburning or sparks and other indices of irregularity.

Figs. 3 and 4 exemplify the application of the accessory collector C forthe auton'latic adjustment of the main collector 0 when the coils of thearmature are connected in a closed circuit, as in the Gramme, Siemens,or other similar forms. The dotted lines in Figs. 3 and at are supposedto pass through those segments on opposite sides of the commutatorpossessing the maximum positive and negative potentials, or throughthose segments at which the two branches of the circuit through thearmature-coils join. When, in this instance, the accessory collector Ois in contact with the most positive segment, as shown in Fig. 3, thecurrent circulates through it and through the coils of thecontact-making electro-maguet A to the main collector (J. In consequenceof said current in the magnet A, contact is effected between points, asin Fig. 2, q, followed by an adjustment of the connnutatorcollectors CO, 850., in the direction as shown by the arrow K, Fig. 3that is, in thedirection of revolution of the commutator, bringing in this manner themain collector C over the dotted line or segments of greatest positivepotential. If, new, from any cause the collectorsG (J are too farforward for effective action, an opposite movement of said collectors isnecessary. This condition is shown in Fig. at, where the dotted lineindicating the points at which the two branches of the circuit throughthe armature-coils join is on the other side of the collector 0 fromthat shown in Fi 3. In this case the current through the elcctro-magnetA is in the opposite direction to that in Fig. 3, in consequence of theaccessory collector 0 being in contact with a commutator strip orsegment less positive than 0. The magnet A, or its armature B, beingpermanently polarized, as we have already stated, the current passing,as in Fig. 4, producing the opposite effect from that in Fi 3, areadjustment of the com mutator-collectors (J and 0 takes place, asshown by the arrow Y, Fig. 4, opposite to the direction of revolution ofthe commutator, thus bringing the main collector (J again over thesegment through which the dotted line passesviz., the segment of highestpositive polarity. The closeness of these adjustments is regulated bythe tension given to the spring S, Fig. 2, which serves to modify theaction of the electromagnet A upon its armature in closing thecontact 1) q.

When the contact 1) q, Fig. 2, is open, the magnet M being inactive, thespring S moves the collectors in one direction, and when said contact isclosed, the magnet M being active, moves said collectors in the oppositedirection. During normal action, however, an intermittent contact at p qtakes place in consequence of the constant tendency of the spring S tomove the collectors. This results in an intermittent action of themagnet M just sufficient to counteract said constant tendency of thespring S when a slight movement of the collector has been caused by thespring. Thus a feeble vibratory movement of the collectors is produced,moderated by the dash-pot D. A condition of equilibrium between theforce of the spring S and the intermittent impulses of the magnet M istherefore assumed and maintained.

By means of the adjusting device thus described the injurious effects ofclosed circuits in armatures the coils of which are connected in acontinuous series may be greatly lessened, and the constructionsimplified by the employment of a smaller number of coils upon saidarmatures.

From the foregoing description itwill be readily understood that theaccessory collector G serves, as it were, the purpose of a feeler, thedesign of which is to test the electrical condition of the segments ofthe commutator at the moment of leaving the collectors, and to originatefrom said condition an adjustment of said collectors in whateverdirection is needed to secure efficient action.

We claim 1. The hereinbetore-described art of automatically adjustingthe collecting-brushes of a dynamo-electric machine, consisting in making said adjustment directly dependent on the electrical condition of thecommutator-segments on leaving said collectingbrushes.

2. In combination with a commutator for dynamo-electric machines, anaccessory collecting-brush, (one or more,) placedin advance of the maincollecting-brush, the currenttaken up by said accessory collector beingutilized in the manner substantially, as shown, to determine theadjustment of the commutator collecting-brushes and to hold saidcollectors in adjustment duriu g operation.

3. The combination, with a dynamo electric machine, of a maincollecting-brush and an accessory collecting-brush, connected to oneanother through the coils of an electro-magnetic device, by theoperation of which an automatic adjustment of said collecting-brushes iseffected.

4. Ina dynamo-electric machine, for the purpose of controlling theadjustment of the commutator collectingbrushes, an electro-magneticdevice, polarized or unpolarized, operating as a contact-maker by meansof the current derived from an accessory collectingbrush, substantiallyas described.

5. The combination, in a dynamo-electric machine, with main andaccessory commutator collecting-brushes, of an electromagnetic deviceoperated by a current resulting from a difference of potential of saidmain and accessory collecting brushes, which clectro magneticdeviceserves, in turn, to operate a suitable motor for the automaticadjustment of said commutator collecting-brushes.

6. As a motor for eifecting the adjustment of the commutatorcollecting-brushes, an electro-magnet, M, traversed by the current or aportion of the current of the machine, whose attraction. upon itsarmature N moves said commutator collecting-brushes in one direction,motion in the other direction being obtained by the action of a spring,substantially as described.

7. The combination, in a dynamo-electric machine, of a contactmakeroperated by the current resulting from a difference of poten' tial ofthe main and accessory collecting brushes with an electromagnetic motorplaced in a shunt or derived circuit around any portion of thefield-magnet coils, said shunt or derived circnit to be closed or openedby said contact-maker, as may be required for the automatic adjustmentof the commutator collecting-brushes.

ELIHU THOMSON. EDWVIN J. HOUSTON.

Witnesses J. R. MASSEY, ROWLAND Evans.

